This is a proposal to acquire a PerkinElmer IVIS SpectrumCT multimodal whole-body small animal imaging system to upgrade our current IVIS 200 series model (purchased in 2007) in order to provide enhanced capabilities within the Wistar Institute Imaging Shared Resource. This instrument upgrade is needed in order to provide state-of-the-art support for 5 major and 5 minor users with 17 R01/R21/P01/P50/U01 NIH-funded research awards. The majority of the projects in this application are cancer based and include melanoma, ovarian, breast, and brain tumor mouse models. The rationale for this request rests on a careful assessment based on the following factors: 1. A need to improve whole-body, small animal imaging capabilities as crucial for the work of current NIH- funded investigators and the anticipated growth in Wistar Institute programs. 2. Our current IVIS 200 model is only capable of quantitative 2D rendering. In contrast, the IVIS SpectrumCT can do quantitative 3D measurements of tumor volumes and metastases using both fluorescence and bioluminescence. 3. The microCT low-dose x-ray scanner will provide an integrated optical and anatomical reference mode for soft tumors and analysis of bone morphology. 4. The IVIS SpectrumCT will provide greater sensitivity for fluorescent probes due to the addition of transillumination excitation, an upgraded camera, better filter sets, and spectral unmixing. 5. Due to the age of our current IVIS 200, it requires more frequent repairs, which is increasing downtime and inconveniencing users. While a major overhaul of failing parts could be undertaken, it is essentially outdated technology that cannot be upgraded to the capabilities of the requested IVIS SpectrumCT. 6. The continuing expansion of the user base for our current IVIS 200 indicates an upward trajectory in the expected number of hours that the upgraded SpectrumCT would be used. The Wistar Institute Imaging Shared Resource is a well-regarded facility, which was established over 25 years ago. It is currently staffed by two experienced technicians and monitored by a faculty user committee. The Imaging and Animal Shared Resources collaborate closely for proper management of the IVIS instrument because it must be maintained behind an animal quarantine barrier. We are proposing to upgrade to an IVIS SpectrumCT due to the significant technical limitations of our current system, the need for advanced imaging features, and the deteriorating condition of our current instrument. A new IVIS SpectrumCT system would provide state-of-the-art whole body, small animal imaging capabilities to our current users and opportunities to expand analyses in future studies.